STAT303 Secs 102 & 103Summer I 2001Exam #2Form AInstructor: Julie Hagen Carroll1. Don’t EVEN open this until you are told to do so.2. Be sure to mark your section number and your test form (A, B, C or D) on the scantron!3. Sign your name where indicated on your scantron and write your section number and computer numberbeside it. You will NOT get your scantron and exam back, but I will keep them in case there is aproblem.4. There are 20 multiple-choice questions on this exam, each worth 5 points. There is partial credit. Pleasemark your answers clearly on the scantron. Multiple marks will be counted wrong.5. You will have 60 minutes to finish this exam.6. If you are caught cheating or helping someone to cheat on this exam, you both will receive a grade ofzero on the exam. You must work alone.7. This exam is worth 100 points, and will constitute 20% of your final grade.8. Good luck! Remember 2 down, you’re halfway there!1STAT303 102 & 103 Exam #2, Form A Summer I 20011. Z ∼ N(0, 12). What P (Z > 0.26)?A. 0.6026B. 0.64C. −0.64D. 0.3974E. 0.36Respondent’| Respondent’s genders income| 0-Female 1-Male | Total-----------+----------------------+----------0-<$20K | 114 68 | 1821->=$20K | 106 111 | 217-----------+----------------------+----------Total| 220 179 | 399Pearson chi2(1) = 7.6089 Pr = 0.0062. Which of the following is a true statement aboutthe data represented above?A. Gender and Income are strongly correlatedsince the p-value = 0.006.B. Gender and Income are dependent cate-gories since the p-value = 0.006.C. Males makes 6% more than females.D. Most females make $20,000 or less.E. All of the above are true statements.3. The correlation coefficient, r, for x and yA. is always between 0 and 1.B. indicates whether x causes y.C. doesn’t matter which variable is x andwhich is y.D. All of the above are true statements.E. None of the above are true statements.4. X ∼ N(4, 22). What is P (0 < X < 4)?A. 0.4772B. 0.5, the upper half of the normal curveC. 0.5, the lower half of the normal curveD. 0.0228E. 0.0255. What does ‘knowing the distribtution of thedata’ tells us?A. the shape, center and spreadB. the possible valuesC. the number of observationsD. All of the above are true.E. Exactly two of the above are true.6. How would we best determine the probability ofgraduating once you finished your freshman year(i.e., we’re NOT talking about including incom-ing freshman)?A. follow our class for the next 2-3 years(since everyone has completed their fresh-man year) and calculate the proportion whoactually get their degreeB. ask a random sample of ‘new’ sophomoreswhether they plan on graduating and cal-culate the sample proportionC. calculate the proportion of graduates, oncethey all graduated, out of the total numberin their class their sophomore yearD. calculate the proportion of recent graduates(Class of ’01) out of the total number intheir class their sophomore yearE. calculate the proportion of graduates of arandom class out of the total number intheir class their sophomore year7. Z ∼ N(0, 12). What is z∗such that P (Z >z∗) = 0.58?A. −0.2B. 0.719C. 0.6628D. 0.2810E. 0.28. Which of the following best defines the p-value,(the ‘Pr =’ part), for the χ2statistic when as-sessing a statistically significant relationship?A. It is the likelihood that the two categoriesare independent.B. It is the likelihood that the two categoriesare dependent.C. It is the likelihood of seeing this strong ofa relationship when there really isn’t anyrelationship.D. It is the likelihood of seeing this strong ofa relationship when there really IS a rela-tionship.E. Two of the above are correct.2STAT303 102 & 103 Exam #2, Form A Summer I 2001| pctresid pctcomm pctindus pcttrans---------+-----------------------------------pctresid | 1.0000|pctcomm | 0.7211 1.0000| 0.0000|pctindus | -0.7421 -0.8352 1.0000| 0.0000 0.0000|pcttrans | -0.0248 0.1882 -0.5987 1.0000| 0.8644 0.1906 0.00009. The table above gives the correlation coefficientsfor the percent residential, commercial, indus-trial and transportation BTU consumption of thetotal for a state. Which two variables have thestrongest correlation?A. We would need a p-value to determinewhether they are related or not.B. Percent residential and percent commercialhave the strongest correlation.C. Percent residential and percent transporta-tion have the strongest correlation.D. Percent industrial and percent commercialhave the strongest correlation.E. Percent industrial has the strongest corre-lation since it has the largest r’s.10. How can we determine probabilities?A. through simulationB. from a random sampleC. from a mathematical formula/equationD. All of the above are true.E. Exactly two of the above are true.11. X ∼ N(4, 22). What is P (X < 8)?A. 0.8413B. 0.9332C. 0.9772D. 0.9999E. 112. Suppose we have the least squares equation forpredicting y = 4.9 + 10.3x. Which of the fol-lowing best describes the point (5, 50), assumingthat this is a valid point from the dataset (withinthe range of x and y)?A. The corresponding point on the line wouldbe 56.4, so it would be off the line and thecorrelation would decrease.B. The corresponding point on the line wouldbe 56.4, so it would be off the line and thecorrelation would increase.C. The corresponding point on the line wouldbe 51.5, so it would be quite near the lineand the correlation would be about thesame.D. The corresponding point on the line wouldbe 34.8, so it would be off the line and thecorrelation would decrease.E. The corresponding point on the line wouldbe 34.8, so it would be off the line and thecorrelation would increase.13. The sample proportion of red M&M’s, in bagswith a total of 50, is pred∼ N(0.2, (0.0572). Howlikely are you to get only 2 reds (so pred= 2/50 =0.04)? What is P (pred≤ 0.04)?A. −2.81B. 0.0025C. 0.025D. 0.0218E. −2.01714. Which of the following is NOT something wewould know from a probability?A. how likely a specific outcome is to occurB. when a specific outcome will occurC. how often a specific outcome will occur inthe long runD. We wouldn’t know any of the above.E. We would know A, B and C.15. Z ∼ N (0, 12). What is z∗such that P (−z∗<Z < z∗) = 0.25?A. ±0.675B. 0.625C. 0.5987D. ±1.15E. ±0.323STAT303 102 & 103 Exam #2, Form A Summer I 200116. The standard normal distributionA. always has the mean equal to the medianequal to zero.B. always has the standard deviation equal tothe IQR and equal to 1.C. always has the smallest standard
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